CC-1065, which is an antibiotic having antimicrobial activity and antitumor activity, is disclosed in J.Antibiotics, vol.31, p.1211 (1978), and vol.34, p.1119 (1981); and U.S. Pat. No. 4,169,888. Duocarmycin A having analogous structure, and analogues thereof are disclosed in WO87/06265; EP0318056; J.Antibiotics, vol.42, p.1229 (1989); and JP-A-4-99774. Derivatives of CC-1065 are disclosed in EP0359454, JP-A-60-193989, and published Japanese translation of PCT application (Kohyo) 2-502005. Derivatives of duocarmycins are disclosed in JP-A-3-7287, JP-A-3-128379, EP0354583, and EP0406749. These are derived by utilizing directly a basic skeleton of a natural substance, or modification of a natural product. Further, a chemically synthesized pyrroloindole derivative having a trifluoromethyl group on the pyrroloindole ring is disclosed by the inventors of the present invention in JP-A-6-116269.
The inventors of the present invention made comprehensive researches on pyrroloindole derivatives which are effective against solid tumor and is less toxic. Consequently, The inventors found a derivative having a trifluoromethyl group in the pyrroloindole ring, and disclosed it in JP-A-6-116269. In JP-A-6-116269, a prodrug represented by Formula A having a carbamoyl group containing a cyclic amine is disclosed. ##STR3##
The present invention intends to provide a prodrug which forms an active species (a compound of Formula A in which B is hydrogen) in vivo more readily than the prodrug shown in Examples of JP-A-6-116269, and is effective against solid tumor and is less toxic.